Plane on a Treadmill

[CyPlainsDrifter]

You are all crazy. The plane is not moving!! Only the wheels are. No movement, not lift!! Freaks!

Another person who doesn't understand what makes a plane move........

:biglaugh:

21 pages and still growing! Woohoo!

 

[twittkop]

Thank you!

Anyone still want to bet?:wink:

I'm going all in for the plane will takeoff if there is a bookie event. (I've never gone all in on any event so far, but I am fully convinced this is easy money)

 

[Clonehomer]

In theoretical terms the plane will take off. Assuming the treadmill is flat with no incline and the wheels are frictionless, there is no force stopping the propulsion. Thus the plane will move and will take off.

In reality however, you can't create frictionless wheels. The plane will start and the treadmill will compensate thus spinning the wheels. The friction on those wheels will cause the plane to stop and it will not take off. This is impossible to show because in order to stop the plane you would need so much force from friction to match the propulsion that any wheel would melt almost instantaneously.

 

[jbhtexas]

However, I sincerely doubt they're going to put a 727 on your average YMCA running device. :skeptical:

Perhaps not, but you could test a scaled airplane on one of those moving walkways you see in airports... With a little bit of tweaking, those things can be made to go quite fast...

 

[aeroclone08]

In theoretical terms the plane will take off. Assuming the treadmill is flat with no incline and the wheels are frictionless, there is no force stopping the propulsion. Thus the plane will move and will take off.

In reality however, you can't create frictionless wheels. The plane will start and the treadmill will compensate thus spinning the wheels. The friction on those wheels will cause the plane to stop and it will not take off. This is impossible to show because in order to stop the plane you would need so much force from friction to match the propulsion that any wheel would melt almost instantaneously.

So logically, a real aircraft would fall between these two extremes. The IS friction on the wheels, but small such that it is easily overpowered by the aircraft's engines.

 

[DaddyMac]

Perhaps not, but you could test a scaled airplane on one of those moving walkways you see in airports... With a little bit of tweaking, those things can be made to go quite fast...

Probably - and I think that's what they do, isn't it?

After reading all this- I still feel that the original idea of the myth is basically busted. But that the idea isn't plausible in that it seems clear that a treadmill type of device couldn't stop the forward progression of the plane.

 

[Clonehomer]

So logically, a real aircraft would fall between these two extremes. The IS friction on the wheels, but small such that it is easily overpowered by the aircraft's engines.

The small friction would not be overpowered by the treadmill. The treadmill will move fast enough to provide enough friction to stop the plane. This treadmill would have to move many times faster than the plane would be moving from the normal thrust. The fact that the coefficient of friction is small just makes the treadmill have to go faster.

 

[CyPlainsDrifter]

The small friction would not be overpowered by the treadmill. The treadmill will move fast enough to provide enough friction to stop the plane. This treadmill would have to move many times faster than the plane would be moving from the normal thrust. The fact that the coefficient of friction is small just makes the treadmill have to go faster.

While I guess that is REMOTELY possible, it's not really within the bounds of the original question. It clearly stated the treadmill would accelerate to MATCH the speed of the plane, not "spin fast enough to PREVENT forward motion of the plane."

 

[hansen55]

I thought that "match the speed" meant that the treadmill would move as fast as needed to negate the thrust of the jet engines thus the plane would not move. Since the plane wouldn't move, the current jet engines wouldn't force enough air under the wing to provide enough lift for the plane to take off.

I'm going to quit thinking about the problem and start saving my money for a Harrier. Problem solved...if I start saving tomorrow, I should have enough money somewhere around the year 4178.

 

[CloneFan65]

I thought that "match the speed" meant that the treadmill would move as fast as needed to negate the thrust of the jet engines thus the plane would not move.

Problem is, this is impossible. The jet engines are creating friction with the air, not the treadmill.

 

[CYVADER]

so is this going to be aired on mythbusters and if so when? and is there going to be a bookie event on it?

 

[CyinCo]

What if there were snakes on the plane? Would it still fly then?

 

[cmoneyr]

I thought that "match the speed" meant that the treadmill would move as fast as needed to negate the thrust of the jet engines thus the plane would not move. Since the plane wouldn't move, the current jet engines wouldn't force enough air under the wing to provide enough lift for the plane to take off.

I'm going to quit thinking about the problem and start saving my money for a Harrier. Problem solved...if I start saving tomorrow, I should have enough money somewhere around the year 4178.

The point is that the treadmill can't negate the power of the thrust because the friction it creates is so negligible compared to the engines power.

 

[Clonehomer]

The point is that the treadmill can't negate the power of the thrust because the friction it creates is so negligible compared to the engines power.

The friction would increase as the speed increased. Increase the speed enough and the force from friction would match the force from the jet.

 

[CYVADER]

i think this solves it.
[ame=http://www.youtube.com/watch?v=-EopVDgSPAk]YouTube - Plane vs. Treadmill Solved![/ame]

 

[DaddyMac]

Can't wait to get home and see it (YouTube blocked at work)

 

[superdorf]

I already posted that video... and the most definitive answer from "THE STRAIGHT DOPE" over the weekend...

This thread will never end... Welcome to Never Ending Thread V4.

 

[cmoneyr]

The friction would increase as the speed increased. Increase the speed enough and the force from friction would match the force from the jet.

But that's not what this problem is saying, it says the treadmill matches the speed of the plane, at a speed matching the takeoff speed of a plane the friction would not be enough to counteract the engines thrust.

 

[herbicide]

But that's not what this problem is saying, it says the treadmill matches the speed of the plane, at a speed matching the takeoff speed of a plane the friction would not be enough to counteract the engines thrust.

The problem says nothing about the takeoff speed. It only says speed, and this is why we are having this debate.

You infer it as matching take-off speed, where I infer it as simply speed, as in the treadmill goes at whatever speed it needs to keep the plane stationary.

 

[CyPlainsDrifter]

I thought that "match the speed" meant that the treadmill would move as fast as needed to negate the thrust of the jet engines thus the plane would not move. Since the plane wouldn't move, the current jet engines wouldn't force enough air under the wing to provide enough lift for the plane to take off.

I'm going to quit thinking about the problem and start saving my money for a Harrier. Problem solved...if I start saving tomorrow, I should have enough money somewhere around the year 4178.

If that's what it meant, then I think there would have been about 5 posts in this thread. Everyone has pretty much realized from the start that NO FORWARD MOTION equals NO TAKE OFF.